Introduction of CTA-index as Simplified Measuring Method for Thrombus Perviousness

Purpose Thrombus features on admission CT are useful imaging markers for clot characterization, stroke pathogenesis and outcome prediction. In this context, thrombus perviousness is a promising parameter, but reliable assessment in daily clinical practice is demanding. The aim of the present study was to evaluate an easy to assess measuring method for thrombus permeability at the time of admission. Methods The CTA-index, which measures relative thrombus attenuation on admission CTA, was compared to the known perviousness parameter in a cohort of 101 patients with large-vessel occlusions of the middle cerebral artery and correlated to clinical outcome parameters (mRS after 90 days, <= 2 rated as favorable). For validation, this correlation was tested in a second independent cohort (n= 87), and possible associations between the CTA-index and outcome measurements (NIHSS/mRS/mTICI) were assessed. Results In the first cohort a coherence between conventional perviousness measurements and the CTA-index was shown. The CTA-index differed significantly between favorable (-0.55 +/- 0.16) and non-favorable outcomes (-0.64 +/- 0.14,p= 0.01). In the validation cohort this result could be independently reproduced (-0.52 +/- 0.13/-0.70 +/- 0.09,p< 0.01). The CTA-index showed an association with low NIHSS at discharge (p< 0.01), favorable outcome after 90 days (p< 0.001) and with better reperfusion (measured by mTICI score,p= 0.04). Conclusion The CTA-index is an easy to assess imaging parameter on admission CTA in the acute stroke phase and is associated with angiographic and clinical outcome. It can be considered as a simplified measuring method for thrombus perviousness, which is known to provide useful information for further stroke progress and clinical course as well as therapeutic and rehabilitative decisions.